1. Field of the Invention
The present invention relates to a sheet carrying apparatus for carrying a sheet, which is ejected by a sheet output device, to a sheet receiving device.
2. Description of the Related Art
In a sheet output device for applying predetermined processing to sheet materials such as paper, OHP sheets, or the like, and successively ejecting sheets out of the device, it is general that a tray for stacking and receiving sheets ejected from the sheet output device is provided in an ejection portion of the sheet output device. In the case where the number of sheets ejected onto the tray at a time is small, in the case where sheets ejected onto the tray are taken out by an operator soon, or in any other similar cases, the aforementioned tray is often satisfactory. However, in the case where the number of sheets ejected at a time is large, in the case where it is not necessary for an operator to take the ejected sheets out soon, in the case where the ejected sheets cannot be taken out, or in any other similar cases, hundreds of sheets or thousands of sheets are stacked in a short time so that there arises a situation in which the aforementioned tray is unsatisfactory. Therefore, conventionally, in a sheet output device requiring such a large-capacity sheet stacking portion, a large-capacity sheet receiving device such as a stacker, or the like, having a sheet stacking tray provided so as to be able to up/down relative to the ejection portion of the sheet output device is connected to the sheet output device to thereby increase the capacity of the sheet stacking portion.
As described above, in the background art, some types of large-capacity sheet receiving devices such as a sheet receiving device capable of receiving 1500 sheets, a sheet receiving device capable of receiving 3000 sheets, etc., were prepared so that selected one of the sheet receiving devices was connected to the sheet output device. Accordingly, on the maker's side, there was a problem that they had to cost much time for development and design of sheet receiving devices individually. It could not be said that this manner was wise. On the other hand, on the user's side, there was an economical problem as follows. For example, assume that a user purchased a sheet output device with a sheet receiving device capable of receiving 1500 sheets. If the user wished thereafter to replace the sheet receiving device by a sheet receiving device capable of receiving 3000 sheets, the sheet receiving device capable of receiving 1500 sheets which was detached from the sheet output device became useless.
Further, also in terms of handling characteristic, a sheet receiving device capable of receiving 3000 sheets has an advantage that the loading capacity increases but the sheet receiving device has a disadvantage that the increase of the loading capacity makes the work of taking-out sheets difficult. Further, the sheet receiving device capable of receiving 3000 sheets has a tendency that sheet alignment characteristic on the sheet stacking tray is lowered compared with the sheet receiving device capable of receiving 1500 sheets. Taking into account the case where the sheet output device has means for applying after-processing such as bookbinding, or the like, to the ejected sheets, worsening of the sheet alignment characteristic is a fatal defect.